The modes for manufacturing lithium ion batteries (“Li-ion batteries”) are presented in many articles and patents, and the work “Advances in Lithium-Ion Batteries” (ed. W. van Schalkwijk and B. Scrosati), published in 2002 (Kluever Academic/Plenum Publishers) provides a good assessment of them. The electrodes of Li-ion batteries can be produced by means of printing or deposition techniques known to a person skilled in the art (in particular: roll coating, doctor blade, tape casting). These techniques make it possible to produce depositions having a thickness of between 50 and 400 μm. Depending on the thickness of the depositions, their porosities and the size of the active particles, the power and energy of the battery may be modulated.
More recently, other Li-ion battery architectures have appeared. These are primarily all-solid-state thin-film microbatteries. These microbatteries have a planar architecture, that is, they consist essentially of an assembly of three layers forming an elementary battery cell: an anode layer and a cathode layer separated by an electrolyte layer. These batteries are said to be “all-solid-state” because the two electrodes (anode and cathode) and the electrolyte are made of non-porous solid materials. These batteries have an important advantage owing to their superior performance to those of conventional electrolyte-based batteries including lithium salts dissolved in an aprotic solvent (liquid or gel electrolyte). The absence of liquid electrolyte considerably reduces the risks of internal short-circuit and thermal runaway in the battery.
Different vacuum deposition techniques have been used to produce thin-film microbatteries. In particular, physical vapor deposition (PVD) is the technique most commonly used at present to produce these thin-film microbatteries. This technique makes it possible to produce high-quality electrode and electrolyte layers without porosity. These layers are generally thin (generally less than 5 μm) so as not to cause excessive power loss associated with an increase in the electrode thicknesses.
Numerous approaches have been proposed in order to produce all-solid-state batteries. In general, these approaches are based only on high-pressure mechanical compaction of electrode and electrolyte material powders (Journal of Power Sources, 2009, 189, 145-148 H. Kitaura). Nevertheless, the electrode and electrolyte layers obtained are porous and the adhesion between them is not optimal, so that the internal resistance of said batteries is too high and does not enable a high power to be generated.
To improve the performance of all-solid-state batteries, a number of sintering techniques have been used, either using thermal treatments (Journal of Power Sources, 2007, 174, K. Nagata) or pulsed current (Material Research Bulletin, 2008, X. Xu). However, sintering leads to significant shrinkage and/or the use of high temperature. Consequently, it is not possible to perform the all-solid-state electrode deposition on conductive metal substrates, and more specifically aluminum substrates. Indeed, an excessively high temperature would oxidize or significantly deteriorate the metal substrate. Moreover, the layer deposited on the substrate would lead to the appearance of cracks during sintering. These disadvantages require current collectors to be deposited on the ends of the battery cell formed by a cathode/electrolyte/anode stack. Consequently, the restriction associated with the deposition of current collectors does not make it possible to produce a three-dimensional battery assembly, all-solid-state, monolithic, consisting of a plurality of elementary cells.